Although the method described here is applicable to any given microelectromechanical structures, the present invention and the problems addressed here will be explained with reference to MEMS structures (“microelectromechanical systems”) based on silicon.
In particular for use in acceleration sensors or rotation rate sensors, which are based on capacitive measuring methods (capacitive MEMS), or in electrostatically driven micro-actuators (e.g., micromirror devices), microelectromechanical structures generally include one or multiple conductive functional layers, which contain stationary and movable areas. Movable areas are fixed, during manufacture, by a so-called sacrificial layer, which is selectively removed at the end of the manufacturing process.
A method for closing a trench of a micromechanical component is described in German Patent Application No. DE 10 2009 045 385 A1.
A method for forming sacrificial areas is described in U.S. Patent Application Publication No. 2013/0115775 A1.
A method for manufacturing MEMS structures is described in German Patent Application No. DE 10 2006 032 195 A1.
German Patent Application No. DE 10 2009 029 202 A1 describes a micromechanical system and a method for manufacturing a micromechanical system.
Manufacture of large sacrificial cavities is difficult, in particular, since, in particular, an undesirable deformation of a carrier substrate may result, for example, during deposition of correspondingly thick sacrificial layers. This undesirable deformation may be compensated for by complex and expensive additional stress-compensating layers.